1. Field of the Invention
The present invention relates to vehicle signal lamp assemblies, and particularly to such lamp assemblies having a resilient bulb mount for absorbing road shock forces associated with vehicle movement.
2. Description of Prior Developments
Vehicle signal lamp assemblies, such as brake lights, back-up lights and turn signal lights tend to fail prematurely when exposed to excessive road shock forces. Various resilient shock absorption mounts have been developed for shielding the lamp filaments from such road shock forces. U.S. Pat. No. 4,176,391 to Kulik includes a discussion of some of the resilient shock absorption lamp mounting devices that have been proposed.
U.S. Pat. No. 4,176,391 discloses a shock isolating vehicle lamp assembly wherein a signal lamp has a cylindrical metal base inserted into a cylindrical metal socket that is embedded in a rubber block constituting part of a shock isolation mount for the lamp bulb. Two pairs of arms extend in opposite directions from the rubber block to connect with two rectangular support bars. The support bars are fixedly mounted in two horizontal tracks in the lamp housing so that the lamp central axis is vertical.
Vehicle vibrational forces act primarily in the vertical direction so that the support bars oscillate vertically. The connecting arms between the support bars and the rubber block flex in transverse directions, i.e. vertically, so that the rubber block and associated lamp are stabilized against excessive vertical oscillation.
In the arrangement of U.S. Pat. No. 4,176,391, the filaments in the lamp are horizontally oriented. Therefore, any vertical oscillatory motion of the lamp will subject the filaments to transverse bending forces. The relatively thin filament wires are not resistant to such bending forces. It is believed that the filament orientation transverse to the direction of the principle vibratory force can contribute to premature lamp failures.